A common oil well pumping system includes a walking beam mounted upon a horizontally-axised, transverse pivot at the top of a Samson post. One end of the walking beam is connected to a pump rod and the other end is connected to the crank of a drive motor through a connecting rod. Rotation of the crank causes the walking beam to rock or oscillate in a vertical plane to raise and lower the pump rod. The rod-connected end of the walking beam is provided with the familiar “horse head” to keep the pump rod in alignment with the well axis. The opposite end of the walking beam carries a counterbalance weight to offset the weight of the pump rod and minimize the stress on the motor.
When pumping an oil well, both oil and gas may be produced and the capture of the gas is both profitable and better for the environment. Thus, an oil well pumping system can include a compressor unit mounted between the walking beam and a stationary part of the pumping unit for compressing the natural gas produced during the pumping of the oil. Such a compressor unit is called a walking beam compressor because it is activated by engaging a piston rod coupled to the walking beam. The rocking of the walking beam reciprocates the piston to effect intake and compression strokes. As a compressing mechanism compresses the gas, high pressures are created inside the compressor housing, requiring appropriate sealing elements between the compressor housing, the piston rod, and the atmosphere. Traditionally, a piston rod seal may have rubber sealing elements that tend to wear quickly and require replacement. Accordingly, there is a need for an improved piston rod seal assembly that can provide effective sealing between the walking beam compressor and the atmosphere while having an extended lifetime.